The present invention relates generally to dual site supervision for a control channel cellular radio used in a fire alarm reporting system, and more particularly pertains to a method and system of dual site supervision for a control channel cellular radio used in a fire alarm reporting system wherein the standard cell phone software module is modified to operate the cell phone in a nonstandard manner to communicate through two separate cellular base stations.
In UL listed communications systems for reporting fire alarms, two separate communications paths are required. The UL requirement for two separate and independent communication paths for a fire alarm system, when implemented in a telephone line reporting system, requires two separate and independent telephone connections and lines. In such a telephone line reporting system, a test call would be placed periodically (e.g. once daily) and alternately over each of the two telephone connections and lines to ensure that the two telephone connections are operating properly in the event that a real fire had to be reported.
For a cellular telephone reporting system for a fire alarm system, two separate RF signals through two separate cellular base stations would be required, and a test call would be placed periodically (e.g. once daily) and alternately through each of the two separate cellular base stations. However, in conventional control channel cellular radio transmitters, the transmitter itself locates radio channel availability and cell site availability, and the radio is programmed to monitor and use only the single channel and cell site that the radio's logic and programming selects. This limitation makes this class of product ineligible for stand alone fire alarm reporting systems complying with UL requirements.
Accordingly, a problem exists with respect to using a cellular telephone reporting system for a fire alarm system because a cellular telephone is programmed to communicate through only one cell base station and not to communicate through two separate cell base stations. Accordingly, to use a cellular telephone reporting system for a fire alarm system requires that the standard cell phone software module be modified to operate the cell phone in a nonstandard manner to communicate through two separate and independent cellular base stations.
In a typical prior art cell phone, the available cellular control channels are first scanned, and the signal strength of each cellular control channel is measured, and a channel list is developed which sorts and classifies the available cellular control channels according to signal strength, which information is taken advantage of by the present invention.